Method of reinforcing deep excavations



April 5, 1966 H. SCHNABEL, JR

METHOD OF REINFORCING DEEP EXCAVATIONS 5 Sheets-Sheet 1 Filed Nov. 16, 1962 ODOBOBD IOIOIOIIO] OIIQIIO April 5, 1966 H. SCHNABEL, JR 3,243,953

METHOD OF REINFORCING DEEP EXCAVATIONS Filed Nov. 16, 1962 5 Sheets-Sheet 2 INV EN TOR 9 Harry Schmbe. Jr:

T'TORNEYS April 5, 1966 H. SCHNABEL, JR 3,243,953

METHOD OF REINFORCING DEEP EXCAVATIONS Filed Nov. 16, 1962 3 Sheets-Sheet 5 3 INVENTOR Harry Saimaaefi, J31

RNEYS United States Patent 3,243,963 METHOD OF REINFORCING DEEP EXCAVATIONS Harry Schnabel, Jr., 4380 MacArthur Blvd, Washington, D.C. Filed Nov. 16, 1962, Set. N0. 238,158 4 Claims. (Cl. 61--39) This invention relates to earth excavating and more particularly to the reinforcing of the sides of deep earth excavations to support the surrounding ground.

This application is a continuation in part of my pending application Serial No. 854,316 filed November 20, 1959.

The invention is particularly applicable to building excavations and it will therefore be shown and described in connection with such excavations. It will be appreciated, however, that the invention is not limited to building excavations and can be employed in connection with various other types of excavations. The invention is limited, however, to deep, as distinguished from shallow, excavations. So-called deep excavations usually are regarded as being greater than about fifteen feet in depth.

In most deep excavation work, particularly in connection with the construction of foundations or the like in the building trade, it is the usual practice to excavate so as to form vertical sides and support such sides by means of sheeting and bracing disposed in a vertical plane. Many methods are currently used to form this earth restraining vertical sheeting or bracing, such as, for example, wooden boards driven vertically in a row, interlocking steel sheet piling driven vertically, vertical steel soldier beams (rolled steel shapes such as bearing piles) driven into the earth at spaced intervals with horizontally extending wood lagging engaged to such beams restraining the earth therebetween, or holes angered in the earth and filled with concrete so as to form a rough vertical concrete or reinforced concrete wall. In such cases, usually it is still necessary to provide additional support such as horizontal braces in the form of beams extending between opposite sides of the excavated hole and engaged to the vertical sheeting. As is understood, such horizontal braces impair and increase the expense of further excavating or other operations.

When providing vertical sheeting for a deep building excavation by current practices, the first step typically is to drive steel beams, for example, 12 inch bearing piles weighing 53 pounds per lineal foot, the beams being driven vertically and horizontally spaced about 6 to 10 feet on centers. The excavation is then coordinated with the placing of horizontal wooden boards, commonly 3 inches thick, so that the earth face between vertical beams is restrained by the boards. Conventionally, the boards are arranged behind the flanges of adjacent beams, or they are anchored to the beams by suitable means, such as bolts and nuts. In any case, pressure acting against the boards is transmitted to the vertical beams. Horizontal braces are then placed directly against each soldier beam, or a wale is placed horizontally along the sheeting, and braces are positioned against the Wale. Such braces, in most instances, extend transversely between opposite sides of the excavation, crossing each other, and hence, they present obstacles to further excavation. These braces may be made of steel, wood or similar material, and are designed to resist large, essentially horizontal forces which are caused by the earth pushing against the sheeting. For an excavation approximately 30 feet in depth with vertical sides, this force might be calculated to be about 18,000 pounds per lineal foot of wall, with a maximum pressure of 750 pounds per square inch of sheeting.

The present invention has, as its main objective, simplifying and improving current practices, such as those referred to, whereby excavation, material and other costs involved in the construction of earth-restraining walls in deep excavations will be substantially reduced. It is proposed to provide novel methods, techniques and structures for erecting earth-restraining walls, as referred to. More specifically, it is an object of the invention to provide earth-restraining walls inclined from the vertical direction so that the total force and pressure acting against the earth-restraining wall will be greatly reduced, thereby making it possible to construct such walls with less material and at appreciable savings in cost by reducing the required strength for both sheeting and bracing.

Where two such inclined walls are installed on two adjoining sides of an excavation with a corner between the sides, a particular problem arises because of the double inclination at the corner. Consequently, it is a further object of this invention to provide a method and structure whereby inclined supporting walls may be installed to adjoining sides of an excavation and bridging the corner between such sides with the finished structure being characterized by great strength and supporting capacity and the installation being rapid with a minimum of ditiiculty and expense.

In general, the temporary earth restraining wall or sheeting of the present invention comprises generally upright piles which are driven into the earth at some predetermined batter or angle to the vertical with elongated narrow sheeting members engaging and extending trans versely of the piles. More particularly, the invention relates to a method of producing a reinforced deep excavation which comprises inserting in the ground a plurality of generally upright piles at spaced intervals in two intersecting planes defining a corner of an area to be excavated and inclined from the vertical away from said area with two of said piles in different ones of said planes adjacent said corner having their upper portions spaced apart further than their lower portions, excavating only from the area inside of said planes to provide a deep excavation having its bottom intermediate the length of said piles while leaving the ground outside of said planes substantially undisturbed, and progressively engaging to said piles from the top down as the excavation proceeds a plurality of elongated narrow sheeting members extending transverse to said piles along the sides of the excavation and bridging said corner between said two sides with the lengths of the members bridging said corner between said two piles being progressively shorter toward the bottom of the excavation, said progressive engagement being accomplished at a rate relative to said excavating to retain the ground outside of said planes in a substantially undisturbed condition.

Further objectives and advantages of the invention will be in part obvious and in part pointed out hereinafter.

The novel features of the invention may be best made clear from the following description and accompanying drawings in which:

FIGURE 1 is a fragmentary vertical sectional view taken along line 1-1 of FIGURE 3 and illustrating an earth-restraining wall or sheeting constructed in accordance with the invention;

FIGURE 2 is a fragmentary plan view of the wall shown in FIGURE 1;

FIGURE 3 is a fragmentary front elevational View of the wall of FIGURE 1;

FIGURE 4 is a View corresponding to FIGURE 1 and showing another embodiment of the invention;

FIGURE 5 is a view corresponding to FIGURE 1 and showing still another embodiment of the invention with the sheeting installed on two adjoining sides of an excavation;

FIGURE- 6 is. a top plan view of the embodiment of .HQUR 5.;

FIGURE 7 is a top plan view of yet another embodiment of the invention; and

FIGURE 8 is a-top, plan view of still another embodiment of the invention.

Referring now to the drawings, there is illustrated in FIGURES 13 an exemplary earth-restraining sheeting or wall 20 Constructed in accordance with the invention. This wall is shown as comprising steel piles or soldier beams 21, arranged at an angle A to the vertical, elongated narrow wood sheeting members or wood lagging 22, av steel wale 24 and a steel brace 26 suitably secured together, as will be explained in more detail hereinbelow. The sheeting 29 slopes downwardly and away from the top surface 28 of the earth, as indicated, and operates to restrain or hold back the earth 29 between top surface 28 and lower surface 30, as will be apparent. The size of angle A may vary, depending on various conditions, such as. the character of the earth, the strength of the wall 2%), etc. An illustrative, although not limiting, range for this angle would be from about to about The lower surface 30 will be intermediate the lengths of piles .21 to afford the latter a substantial penetration into the ground below the surface 39 for strength purposes.

The invention has special application to building excavations, and hence, an exemplary method for the construction of wall 20 in connection with building excavations will now be described.

, Assuming that all or most of the earth, in the proposed building site, isapproximately at the level of surface 28, the steel beams 21 will initially be driven into the earth at spaced intervals in a common plane at a predetermined angle A to the vertical and to a predetermined depth. ,The number of and spacing between these beams 21 will vary according to the particular job requirements, as will be evident as the description proceeds. Usually the beams 21- will be situated parallel to each other in their common plan The. earth will then be excavated in the region of the topsof; these beams, and the first or upper horizontal row of woodlagging 22 may then be engaged to these beams 21 andiabu t or press against the sloped surface of the earth. Anysuitable means may be utilized for securing the wood lagging to the beams 21. For example, they may be disposed to the rear of the front flange 32 of the beams and held in secure engagement therewith by the pressure of the earth.

As the excavation proceeds, additional horizontal rows of thewood lagging may be similarly arranged in engagement; with the beams 21 and abutting the earth, until the desired depthis reached. It will be appreciated that each successively lower horizontal row of wood lagging 22 maybe secured to the beams 21 in step-by-step fashion coordinated. with the progress of the excavation. The depth of excavation below the top of the original ground or the lowermost lagging 22 is limited to that depth at which'tbe surrounding ground will remain in a substantially. undisturbed condition. without caving. However, the excavation may proceed to a substantial, suitable depth before any additional rows of lagging 22 are installed, since, by reason of the fact that the face of the earth 29 will be sloped during the excavation, the earth will stand for. a greater timexand to a greater depth Without any danger of collapsing. Thus, a larger portion, if not all, of the excavation near the sheeting or wall 26 may be done cheaply by machine. This is in sharp contrast to present practices in building excavations wherein it is necessary to perform an undesirably large part of the excavating work by hand, thereby adding considerably to the time and expense necessary to complete the job.

Inasmuch as the earth pressure acting on the sheeting 2tl-will not be as great as if'the sheeting were vertical or substantially vertical, it will be possible to use the same size boards '22 when the spacing between beams 21 is increased, or to reduce the thickness of the boards if beam spacing is maintained, or sheet metal tension members of approximately the same length and width as the boards 22 may be used in lieu thereof, if preferred. Obviously, if the pressure acting per linear foot of wall is reduced by the inclining of the face, the wales and braces may be reduced in size or spread out.

A space 4!) may be provided between adjacent rows of lagging 22, as shown, to allow ground water to seep into the excavation, and the size of this space may be increased or decreased, as desired, so long as adequate support will be provided for the earth. Vertical planks 42 may be suitably attached to the lagging 22, adjacent the beams 21, as shown.

The steel wale 24 is shown as extending across the front flanges 32 of beams 21, and it may be secured thereto in the position shown by any suitable means, such as by welding. Wedges 44 may be used between the wale and the'flanges, 32 of the beams 21 in order to mount the wale in the position shown. These wedges may be welded or otherwise secured to both the beams 21 and the wale 24.

The steel brace 26 is shown as being engaged to the 'wale, as by welding, and extending downwardly therefrom to the surface 36. In some cases, the wales 24 and braces 26 may be omitted or reduced in size.

It will be appreciated that sheeting similar to sheeting .20 may be similarly erected around the peripheral sides of a building excavation as will be hereinafter described.

FIGURE 4 illustrates an arrangement utilizing tie-back cables of suitable construction, such' as rope or metal, secured to the tops of beams 21 and extending rearwardly to an anchor 52. There may be provided one anchor 52 for each cable 55 or one anchor may be provided for all of the cables. Anchor 52 may, for example, be in the form of a concrete post or a steel beam set in a drilled hole and concreted in; There preferably will be one cable 50 for each beam 21, and these cables will be appropriately lashed thereto and to the posts 52.

As previously indicated, one of the outstanding virtues of the present invention is that it enables earth-restraining walls to be constructed in deep excavations with considerable savings in time, materials, and cost as a result of the reduction in earth pressures occasioned by arranging the wall at an angle to the vertical, as described.

Illustrated in FIGURES 5 and 6 is another embodiment of the invention similar to that of FIGURE 1 except that the wooden sheeting members or lagging 22 are not spaced apart vertically but are stacked directly on top of each other. Moreover, FIGURES 5 and, 6 illustrate a particularly advantageous facet of the invention which facilitates installation of the inclined sheeting around a corner of an excavation.

Asbest shown in FIGURE 6 the piles-21 are installed at spaced, preferably parallel locations in each of two planes which define the sides of the excavation and intersect at a corner. As previously described, each of such planes are inclined from the vertical away from the excavation. The two piles 21' which are nearest the corner of the excavation havetheir upper portions spaced apart further than their lower portions as a result of their different inclinations in different planes. As a consequence the piles 2'1. define a triangle or a trapezoid between them. The corner between thetwo piles 21' may be bridged by inserting between the flanges of such piles a pluralityof wood lagging or. sheeting members 21 which extend directly between the two piles 21' across the two planes in which the piles lie. Further, the length of the members 22. becomes progressively shorter toward the bottom of the excavation. Using the method of the present invention, it is a relatively simple matter to progressively insert the increasingly shorter members 22' as the excavation proceeds. Any attempt to bridge the'corner by a solid'member such as sheet piling or the like, however, would pose a substantialif not insurmountable problem. In that case a triangular or trapezoidal solid member which fills the corner space would have to be driven into the ground in such a manner that would permit connection to the piles 21. If it could be done, at all, it would require a highly precise operation which would greatly increase the cost of the project. In contrast the corner structure of the present invention can be easily and quickly installed by relatively unskilled laborers.

A variation of both the manner of connection of the sheeting members to the piles and the corner construction is shown in the embodiment of FIGURE 7. In such embodiment the sheeting members 22 extend continuously across more than two piles and are engaged to the front face of the piles by suitable connections 51. In FIGURE 7 the sheeting members 22 are shown in vertical spaced relation. As previously stated, such spacing could be varied or eliminated entirely.

In the FIGURE 7 embodiment the sheeting members 22 are extended toward the corner beyond the piles 21' along the same plane in which the sides of the excavation and the piles 2]. lie. Thus, the sheeting members 22 from the two adjoining sides of the excavation meet along the intersection of the planes which define such sides. A corner pile 22 may be driven with a double inclination to make it lie in both such planes along the intersection between the planes. Then the ends of the sheeting members 22 may be connected to each other and to the pile 22".

If desired, the corner pile 22" may be eliminated as illustrated in FIGURE 8. The driving of such a pile with the exact double inclination required necessitates a egree of precision which cannot always be justified. Where no corner pile is used, the ends of the sheeting members, which meet along the intersection of the two planes which define the sides of the excavation, may be connected together as by nailing or the like.

In the embodiments of both FIGURE 7 and FIGURE 8 the corner sheeting along one side is preferably passed beyond the ends of the comer sheeting along the other side with the latter butted against the face of the former.

It will be understood that the wales, bracing and any of the other specific features described with respect to FIG- URES 1-4 may be employed with the embodiments of FIGURES 5-8.

The present invention will thus be seen to completely and efiectively accomplish the objects enumerated hereinabove. It will be realized, however, that various changes and substitutions may be made to the specific embodiments disclosed herein for the purpose of illustrating the principles of this invention without departing from these principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

1. In a method of producing a reinforced deep excavation, the combination of steps which comprises inserting in the ground a plurality of generally upright piles at spaced intervals in two intersecting planes defining a corner of an area to be excavated and inclined from the vertical away from said area with two of said piles in difierent ones of said planes adjacent said corner having their upper portions spaced apart further than their lower portions,

excavating only from the area inside of said planes to provide a deep excavation having its bottom intermediate the length of said piles while leaving the ground outside of said plane substantially undisturbed, and

progressively engaging to said piles from the top down as the excavation proceeds a plurality of elongated narrow sheeting members extending transverse to said piles along the sides of the excavation and bridging said corner between said two sides with the lengths of said members between said two piles being progressively shorter toward the bottom of the excavation, said progressive engagement being accomplished at a rate relative to said excavating to retain the ground outside of said planes in a substantially undisturbed condition.

2. A method according to claim 1 wherein said members bridging said corner extend from said two piles in said planes and meet at the intersection between said planes.

3. A method according to claim 2 wherein a corner pile lying in both of said planes is driven along said intersection and the ends of said members are engaged to said corner pile.

4. A method according to claim 1 wherein said members bridging said corner extend across said planes directly between said two piles.

References Cited by the Examiner UNITED STATES PATENTS 465,107 12/1891 Becker 61-39 718,441 1/1903 Ewen 6139.1 X 1,644,288 10/1927 Stehlow 61-39 2,830,588 4/1959 Moore 6139 3,068,565 12/1962 Booth et al 61-41 3,114,244 12/1963 Silver 61-49 OTHER REFERENCES Armco Handbook of Drainage and Construction Products: published by Armco D and M Products, Middleton, Ohio, 1958, page 387.

Construction Methods of April 1956, pp. 74-75. Construction Methods and Equip: published June 1958, pages 102104.

CHARLES E. OCONNELL, Primary Examiner.

JACOB SHAPIRO, Examiner. 

1. A METHOD OF PRODUCING A REINFORCED DEEP EXCAVATION, THE COMBINATION OF STEPS WHICH COMPRISES INSERTING IN THE GROUND A PLURALITY OF GENERALLY UPRIGHT PILES AT SPACED INTERVALS IN TWO INTERSECTING PLANES DEFINING A CORNER OF AN AREA TO BE EXCAVATED AND INCLINED FROM THE VERTICAL AWAY FROM SAID AREA WITH TWO OF SAID PILES IN DIFFERENT ONES OF SAID PLANES ADJACENT SAID CORNER HAVING THEIR UPPER PORTIONS SPACED APART FURTHER THAN THEIR LOWER PORTIONS, EXCAVATING ONLY FROM THE AREA INSIDE OF SAID PLANES TO PROVIDE A DEEP EXCAVATION HAVING ITS BOTTOM INTERMEDIATE THE LENGTH OF SAID PILES WHILE LEAVING THE GROUND OUTSIDE OF SAID PLANE SUBSTANTIALLY UNDISTURBED, AND PROGRESSIVELY ENGAGING TO SAID PILES FROM THE TOP DOWN AS THE EXCAVATION PROCEEDS A PLURALITY OF ELONGATED NARROW SHEETING MEMBERS EXTENDING TRANSVERSE TO SAID PILES ALONG THE SIDES OF THE EXCAVATION AND BRIDGING SAID CORNER BETWEEN SAID TWO SIDES WITH THE LENGTHS OF SAID MEMBERS BETWEEN SAID TWO PILES BEING PROGRESSIVELY SHORTER TOWARD THE BOTTOM OF THE EXCAVATION, SAID PROGRESSIVE ENGAGEMENT BEING ACCOMPLISHED AT A RATE RELATIVE TO SAID EXCAVATING TO RETAIN THE GROUND OUTSIDE OF SAID PLANES IN A SUBSTANTIALLY UNDISTURBED CONDITION. 